1f627d34f1
According to the GeoJSON specification [1]: > * A linear ring is a closed LineString with four or more positions. > * The first and last positions are equivalent, and they MUST contain > identical values; their representation SHOULD also be identical. > (...) > * For type "Polygon", the "coordinates" member MUST be an array of > linear ring coordinate arrays. Note that, for simplicity, right now we aren't checking whether the coordinates are defined counterclockwise for exterior rings and clockwise for interior rings, which is what the specification expects. [1] https://datatracker.ietf.org/doc/html/rfc7946#section-3.1.6
128 lines
3.6 KiB
Ruby
128 lines
3.6 KiB
Ruby
class GeojsonFormatValidator < ActiveModel::EachValidator
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def validate_each(record, attribute, value)
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if value.present?
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geojson = parse_json(value)
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unless valid_geojson?(geojson)
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record.errors.add(attribute, :invalid)
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return
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end
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unless valid_coordinates?(geojson)
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record.errors.add(attribute, :invalid_coordinates)
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end
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end
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end
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private
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def parse_json(geojson_data)
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JSON.parse(geojson_data)
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rescue JSON::ParserError
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nil
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end
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def valid_geojson?(geojson)
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return false unless geojson.is_a?(Hash)
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if geojson["type"] == "FeatureCollection"
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valid_feature_collection?(geojson)
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elsif geojson["type"] == "Feature"
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valid_feature?(geojson)
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else
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valid_geometry?(geojson)
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end
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end
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def valid_feature_collection?(geojson)
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return false unless geojson["features"].is_a?(Array)
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geojson["features"].all? { |feature| valid_feature?(feature) }
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end
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def valid_feature?(feature)
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feature["type"] == "Feature" && valid_geometry?(feature["geometry"])
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end
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def valid_geometry?(geometry)
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geometry.is_a?(Hash) && valid_geometry_types.include?(geometry["type"])
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end
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def valid_geometry_types
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[
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"Point", "LineString", "Polygon", "MultiPoint", "MultiLineString", "MultiPolygon",
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"GeometryCollection"
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]
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end
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def valid_coordinates?(geojson)
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if geojson["type"] == "FeatureCollection"
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geojson["features"].all? { |feature| valid_coordinates?(feature) }
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elsif geojson["type"] == "Feature"
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valid_geometry_coordinates?(geojson["geometry"])
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else
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valid_geometry_coordinates?(geojson)
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end
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end
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def valid_geometry_coordinates?(geometry)
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if geometry["type"] == "GeometryCollection"
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geometries = geometry["geometries"]
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return geometries.is_a?(Array) && geometries.all? { |geom| valid_geometry_coordinates?(geom) }
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end
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coordinates = geometry["coordinates"]
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return false unless coordinates.is_a?(Array)
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case geometry["type"]
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when "Point"
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valid_wgs84_coordinates?(coordinates)
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when "LineString"
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valid_linestring_coordinates?(coordinates)
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when "MultiPoint"
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valid_coordinates_array?(coordinates)
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when "MultiLineString"
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coordinates.all? do |linestring_coordinates|
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valid_linestring_coordinates?(linestring_coordinates)
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end
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when "Polygon"
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valid_polygon_coordinates?(coordinates)
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when "MultiPolygon"
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coordinates.all? do |polygon_coordinates|
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valid_polygon_coordinates?(polygon_coordinates)
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end
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else
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false
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end
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end
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def valid_wgs84_coordinates?(coordinates)
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return false unless coordinates.is_a?(Array) && coordinates.size == 2
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longitude, latitude = coordinates
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(-180.0..180.0).include?(longitude) && (-90.0..90.0).include?(latitude)
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end
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def valid_coordinates_array?(coordinates_array)
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coordinates_array.is_a?(Array) &&
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coordinates_array.all? { |coordinates| valid_wgs84_coordinates?(coordinates) }
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end
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def valid_linestring_coordinates?(coordinates)
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valid_coordinates_array?(coordinates) && coordinates.many?
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end
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def valid_polygon_coordinates?(polygon_coordinates)
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polygon_coordinates.is_a?(Array) &&
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polygon_coordinates.all? { |ring_coordinates| valid_ring_coordinates?(ring_coordinates) }
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end
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def valid_ring_coordinates?(ring_coordinates)
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valid_coordinates_array?(ring_coordinates) &&
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ring_coordinates.size >= 4 &&
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ring_coordinates.first == ring_coordinates.last
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end
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end
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